To estimate a distance between a transmitter and a receiver in a wireless communications network, the transmitter can send a signal to the receiver at a time t1. The receiver, as soon as possible, returns a reply signal to the transmitter. The transmitter measures the time of arrival (TOA) of the reply signal at time t2. An estimate of the distance between the transmitter and the receiver is the time for the signal to make the round trip divided by two and multiplying by the speed of light, i.e.:
  D  =                                                  t            1                    -                      t            2                                      2        ⁢          c      .      
Accurate time resolution of ultra wideband (UWB) signals facilitates very precise positioning capabilities based on signal TOA measurements. Although a theoretical lower bound for TOA estimation can be achieved by using maximum likelihood methods, those prior art methods are impractical due to a need for extremely high sampling rates and a large number of multipath components of the signal.
Another method is correlation-based. That method serially searches possible signal delays of a signal received via a first signal path and takes a very long time to estimate the TOA of the received signal.
Moreover, the signal received from the first path does not always have a strongest correlation output, which can result in an inaccurate TOA estimate by the prior art correlation-based methods.
Therefore, there is a need for a time of arrival estimation method that overcomes the problems of the prior art.